[es6] Object.getOwnPropertyDescriptor should wrap primitives

test/mjsunit/get-own-property-descriptor-non-objects.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+assertThrows(function() {
+  Object.getOwnPropertyDescriptor(null, 'x');
+}, TypeError);
+
+
+assertThrows(function() {
+  Object.getOwnPropertyDescriptor(undefined, 'x');
+}, TypeError);
+
+
+assertEquals({
+  configurable: false,
+  enumerable: false,
+  value: 3,
+  writable: false,
+}, Object.getOwnPropertyDescriptor('abc', 'length'));
+
+
+assertEquals({
+  configurable: false,
+  enumerable: true,
+  value: 'a',
+  writable: false,
+}, Object.getOwnPropertyDescriptor('abc', 0));
+
+
+assertSame(undefined, Object.getOwnPropertyDescriptor(42, 'x'));
+assertSame(undefined, Object.getOwnPropertyDescriptor(true, 'x'));
+assertSame(undefined, Object.getOwnPropertyDescriptor(false, 'x'));
+assertSame(undefined, Object.getOwnPropertyDescriptor(Symbol(), 'x'));